The present invention relates to a system for automatically bringing a motor vehicle into a target position, having a sensor system and an analyzing unit for determining the position of the motor vehicle relative to the target position as well as devices for planning a collision-free drive from the current position to the target position and devices for implementing the planned drive.
A method of bringing a motor vehicle into a target position is known from European Patent Document EP 1 249 379 A2, by which the motor vehicle is brought into a starting position close to the endeavored target position. After a first driver-side activation, the environment of the motor vehicle is continuously scanned at least for the detection of the target position, and the current vehicle position is continuously determined. Based on the determined environmental and position information, control information is determined for bringing the motor vehicle into the target position. After a second driver-side activation, control commands dependent on the control information are emitted to the transmission line and/or the braking system and/or the steering system of the motor vehicle, whereby the motor vehicle drives into the target position independently of the driver.
Such a process is typically triggered by one or more operating actions of an operator situated outside the motor vehicle.
The method known from European Patent Document EP 1 249 379 A2 is suitable for bringing a motor vehicle into various target positions, such as normal parking spaces. This ambitious objective implies that the method should also be usable in unstructured environments, i.e., environments having only natural landmarks. For this purpose, high technical expenditures on the part of the motor vehicle are required for detecting the environment of the motor vehicle and the own position.
It is an object of the present invention to provide a system which permits automatic park-in and/or park-out operations and requires low technical expenditures on the part of the motor vehicle.
According to the invention, this object is achieved by a system for automatically bringing a motor vehicle into a target position, having a sensor system and an analyzing unit for determining the position of the motor vehicle relative to the target position as well as devices for planning a collision-free drive from the current position to the target position and devices for implementing the planned drive, wherein a first part of the sensor system is arranged at or in the motor vehicle, and a second part of the sensor system is arranged in a stationary manner in a defined position close to the target position.
Typically, motor vehicles are repeatedly parked in or out at one of very few target positions. Particularly, parking operations are frequently repeated with respect to a single target position, for example, the vehicle holder's garage at home. According to the invention, by means of the stationary arrangement of the second part of the sensor system in a defined position, the target position or at least an object situated in a stationary manner close to the target position (e.g., the wall of a garage) is prepared for parking operations such that the motor-vehicle-side technical expenditures required for permitting a method of automatically bringing a motor vehicle into a target position can be reduced considerably. As a result of the preparation of the target position or of the at least one object situated in a stationary manner close to the target position, a structured environment is created for the parking operation to be carried out automatically.
A first advantage of a system according to the invention is that technical motor-vehicle-side expenditures are reduced compared to a method according to the state of the art in that the equipment-related expenditures on the part of the motor vehicle are reduced. This advantage may concern the sensor system to be provided on the part of the motor vehicle as well as the computing capacity of an arithmetic-logic unit to be provided on the part of the motor vehicle.
A second advantage of a system according to the invention consists of the fact that the computing expenditures required for implementing a method for automatically bringing a motor vehicle into a target position are reduced and/or the precision and/or robustness of such a method can be increased.
According to a further development of the invention, by means of the sensor system contained in a system according to the invention, at least a horizontal angle between a reference axis of the first or second part of the sensor system and a connection axis between a reference point of the first part and a reference point of the second part of the sensor system can be determined.
This clearly distinguishes a system according to the invention from known park-in aids for garage parking spaces, in the case of which at least one part of a sensor system (e.g., for the ultrasonic ranging) is arranged in a stationary manner close to a target position. As a rule, such systems detect only the distance of a motor vehicle from the target position and thus only a small portion of the measurable quantities required for the implementation of automatic pin-in and/or park-out operations. In addition, in contrast to a system according to the invention, such systems are typically exclusively provided for supporting the driver, for example, by means of acoustic or visual information, during parking operations, in which the motor vehicle is operated by the driver.
According to a first exemplary embodiment of the invention, the first part of the sensor system is arranged in a defined spatial location with respect to the motor vehicle, and the sensor system and the analyzing unit are suitable for determining the horizontal angle between a reference axis of the first part of the sensor system, particularly the longitudinal axis of the vehicle, and a connection axis between a reference point of the first part and a reference point of the second part of the sensor system.
The angle set between the reference axis of the first part of the sensor system and the above-mentioned connection axis, if the axes and reference points are correspondingly defined and analyzed, will supply information as to the direction in which the target position is situated with respect to the motor vehicle.
According to a second exemplary embodiment of the invention, the second part of the sensor system is arranged in a defined spatial location with respect to the target position, and the sensor system and the analyzing unit are suitable for determining the horizontal angle between a reference axis of the second part of the sensor system, particular of a center axis of the garage, and connection axis between a reference point of the first part of the sensor system and a reference point of the second part.
The angle set between the reference axis of the second part of the sensor system and the above-mentioned connection axis, if the axes and reference points are correspondingly defined and analyzed, will supply information as to the direction in which motor vehicle is situated with respect to the target position.
According to a third exemplary embodiment of the invention, the sensor system and the analyzing unit are suitable for determining the distance between a reference point of the first part and a reference point of the second part of the system.
If the reference points are correspondingly defined and analyzed, the distance between the current motor vehicle position and the target position can be derived therefrom.
According to an exemplary embodiment of the present invention, the second part of the sensor system includes at least one so-called artificial landmark. In the industry, artificial landmarks are normally used for preparing the usage environment of autonomous mobile systems, such as driverless transport systems (FTS), in a targeted manner in the production. Their use in connection with motor vehicles has been less widespread. Artificial landmarks are typically mounted in a defined spatial location and/or location, and the sensors of an autonomous system can recognize them in a simple and reliable manner. Artificial landmarks can correspond with sensors of different operating principles, for example, visually and/or acoustically and/or inductively and/or magnetically. They may each have an active or passive design.
Using several landmarks, the position and location of the first part of the sensor system with respect to the second part, that is, the position and location of the motor vehicle with respect to the target position, can be determined in a manner known per se, for example, by triangulation. Such determination methods are known and are based on different measuring principles, for example, visual and/or acoustic and/or inductive and/or magnetic principles.
According to another exemplary embodiment of the present invention, a structured environment is provided for the parking operation to be carried out automatically in that exactly one artificial landmark is mounted in a stationary manner close to the target position.
In order to permit the simple and reliable determination of as many of the above-mentioned quantities as possible, the artificial landmark has to meet certain requirements. According to an exemplary embodiment of the present invention, a passive visual artificial landmark is used which is such that it is suitable for the direction-dependent reflection of incident light.
The passive visual artificial landmark may be designed and/or is spatially arranged such that it is suitable for the horizontally variable reflection of incident light. For this purpose, reflectors are suitable which are based, for example, on lamellae, particularly lamellae of a variable adjusting angle. As an alternative, the use of at least one so-called lenticular image—in colloquial language, also called a wobble image—is conceivable as a passive visual artificial landmark with horizontally variable reflection characteristics or as a part thereof.
According to an exemplary embodiment of the present invention, the second part of the sensor system includes a camera. Analogously, the analyzing unit essentially corresponds to an image processing unit. According to an exemplary embodiment of the present invention, a camera contained in a system according to the invention can be used by at least one other functionality of the motor vehicle. If the camera is used for the implementation of one or more functionalities of the motor vehicle, only very low equipment costs will arise on the part of the motor vehicle for the implementation of a system according to the invention.
In a system according to the last-mentioned embodiment of the invention, the following identification steps can be carried out in a manner known per se:                Identification of the landmark in the camera picture by means of its shape (for example, square or rectangular with a defined height-width ratio);        determination of the distance between a reference point of the camera and a reference point of the landmark from the reduction ratio of the image of the landmark in the taken camera picture;        determination of the horizontal angle between the camera axis or longitudinal vehicle axis and the connection axis between a reference point of the camera and a reference point of the landmark by means of the position of the center of mass of the image of the landmark in the taken camera picture;        determination of the horizontal angle between a reference axis of the landmark, such as a center axis of a garage, and the connection axis between a reference point of the camera and a reference point of the landmark by means of characteristics, particularly brightness characteristics, of the image of the landmark in the taken camera picture.        
In particular, the last identification step is very much dependent on the nature of the selected landmark. According to an advantageous embodiment of the present invention, the nature of the landmark is such that, as a result of its direction-dependent reflection behavior, a course of brightness within the image of the landmark occurs which depends on the angle of view. In the case of a horizontally variable reflection behavior of the landmark, such a course of brightness depends particularly on the horizontal angle of view.
According to an exemplary embodiment of the present invention, the nature of the landmark is such that, in the case of corresponding lighting conditions, within the image of the landmark in the taken camera picture, at least one easily detectable area having essentially the shape of a vertically extending bar occurs, which area has a brightness which differs from the brightness of the surrounding areas. The lateral position of such a vertical bar within the image of the landmark in the taken camera picture, in the case of the corresponding embodiment of the landmark, is clearly connected with the wanted angle. According to exemplary embodiments of the present invention, the nature of the landmark is such that precisely one such bar occurs which has a brightness that is increased with respect to the surrounding areas and/or precisely one such bar occurs which has a brightness that is reduced with respect to the surrounding areas.
In order to create lighting conditions which promote a reliable and precise operating mode of a system according to the invention, the sensor system of a system according to the invention may include its own light source and/or is suitable for activating at least one vehicle head light.
In a system according to the invention, the sensor system and the analyzing unit may be provided as the only devices for determining the position and/or location of the motor vehicle relative to the target position, or further sensor systems may be contained in a system according to the invention which, as required, are provided additionally to the implementation of further functionalities.
The utilization of the at least one sensor system contained in a system according to the invention or of the additional sensor systems may, in each case, concern the planning of a collision-free drive from the current position to the target position and/or its monitoring with respect to the freedom from collision and/or a new planning during the implementation of a drive and/or the triggering of an automatic termination of such a drive or a report to the operator typically situated outside the motor vehicle. Several contained sensor systems are possibly utilized for tasks different from those mentioned above, or certain contained sensor systems are only utilized for some tasks of those mentioned above. In particular, the signals of at least one additional sensor system may be used for checking safety criteria. As an alternative or in addition, information of additional sensor systems can be analyzed in a system according to the invention in the sense of a sensor fusion or a plausibility check.
According to a further development of the present invention, parameters can be utilized when planning a collision-free drive which characterize the position and location of the second part of the sensor system with respect to the target position and/or which characterize the spatial relationships around the target position.
According to further development of the present invention, the sensor system of a system according to the invention has at least two second parts which are each assigned to a target position and are mounted close to this target position.
In particular, the at least two second parts of the sensor system may be constructed such that they can be differentiated from the first part of the sensor system. In this manner, various target positions can be differentiated, and parking operations can be planned and implemented for different target positions in different fashions. Correspondingly, several sets of parameters may be filed in a system according to the invention, which sets each characterize the position and location of a second part of the sensor system with respect to a pertaining target position and/or spatial relationships around a pertaining target position.
By means of the attached drawings, an exemplary embodiment of the invention will be further explained in detail in the following.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.